1. Field of the Invention
The present invention relates to a LED bulb, and, more particularly, to a high illumination LED bulb structure with a 360-degree projection light.
2. Description of the Related Art
As the green energy policy is highly promoted in international society, many advanced countries have thus set up the utilization deadline for tungsten bulbs. Light-emitting diode (LED) bulbs thus gradually enter the replacement market of tungsten bulbs.
The optical sources of traditional tungsten bulb 11 and energy saving bulb 12 project a 360-degree light (as shown in FIGS. 1-2), but the bulb 13 (as shown in FIG. 3) currently based on LED (Surface-Mount Device LED or chip) as optical source can only make projection light in single direction, failing to project the same 360-degree light as the tungsten bulb 11 and the energy saving bulb 12. The LED bulb 13 with single direction projection light can be only utilized in a type of lamp with illumination from the ceiling to the floor. Accordingly, general lamps with upward bulb holders have been replaced by compact fluorescent lamps (CFL) such as HCFL and CCFL when tungsten light bulbs were out of time.
Compact fluorescent lamps, however, still have some drawbacks as follows: (1) Intermittent light from a luminous source activated by variable voltages is unhealthy for eyes during reading. (2) Mercury gas in a compact fluorescent lamp threatens the human body with the lamp broken and some costs are indispensable to disposal of compact fluorescent lamps. (3) Ultraviolet projected from a compact fluorescent lamp is harmful to skin in a short distance. As a result, an LED bulb 14 (as shown in FIG. 4) designed by some LED manufacturers and available currently has a longer transparent bulb shell 141 farther spaced from a luminous source of the LED 142, increasing beam angles due to downward retro-light synchronously generated with projected light which penetrates the transparent bulb shell 141. On the other hand, an LED bulb 15 (FIG. 5) features a longer transparent bulb shell 151 and lifted LEDs 152 as a luminous source which intensifies downward retro-light. However, halo which is radiated under effect of non-direct light such as retro-light intensifies visible light in a room but contributes illumination necessary for reading a little (e.g., D2 from a desk lamp 16 in FIG. 6).
In order to increase beam angles of an LED bulb, alternative LED bulbs 2, 3, 4 (as shown in FIGS. 7, 8, and 9) radiating horizontally was manufactured, but the luminous source of LEDs 21 of the LED bulb 2 of FIG. 7 and the luminous source of LEDs 31 of the LED bulb 3 of FIG. 8 still fail to project light toward bulb holder 22, 32 respectively. Further, the luminous source of LEDs 41 of the LED bulb 4 of FIG. 9 will be blocked by a lower cover 42, failing to project a 360-degree light to improve illumination of a floor lamp, a desk lamp, a wall lamp or a bedside lamp.
Thus, how to design LED bulb with a 360-degree projection light to match the utilization of lamps such as floor lamps, desk lamps, wall lamps or bedside lamps and to increase the illumination scope of the projection light is really the top urgent matter of the LED industries.